Method and apparatus for supporting a polishing pad during chemical-mechanical planarization of microelectronic substrates

ABSTRACT

A method and apparatus for planarizing a microelectronic substrate. In one embodiment, the apparatus can include an elongated polishing pad that is moved over a platen either between or during the planarization cycles, and a support pad that is moved along with the polishing pad. The support pad can be an elongated member that extends between a supply roller and a take-up roller, or can include a continuous member that extends around the spaced apart rollers. The platen can also be movable along with the support pad and can be supported by fluid jets, rollers, or a rotating bladder. Cleaning devices and/or milling devices can treat the surfaces of the polishing pad, the support pad and/or the platen to reduce the likelihood for contaminants to become caught between these components as they engage with each other.

TECHNICAL FIELD

[0001] The present invention is directed toward methods and apparatusesfor supporting a polishing pad relative to a microelectronic substrateduring mechanical and/or chemical-mechanical planarization.

BACKGROUND OF THE INVENTION

[0002] Mechanical and chemical-mechanical planarizing processes(collectively “CMP”) are used in the manufacturing of microelectronicdevices for forming a flat surface on semiconductor wafers, fieldemission displays, and many other microelectronic-device substrates andsubstrate assemblies. FIG. 1 is a partially schematic isometric view ofa conventional web-format planarizing machine 10 that has a platen 20. Asub-pad 50 is attached to the platen 20 to provide a flat, solidworkstation for supporting a portion of a web-format planarizing pad 40in a planarizing zone “A” during planarization. The planarizing machine10 also has a pad-advancing mechanism, including a plurality of rollers,to guide, position, and hold the web-format pad 40 over the sub-pad 50.The pad-advancing mechanism generally includes a supply roller 24, firstand second idler rollers 21 a and 21 b, first and second guide rollers22 a and 22 b, and a take-up roller 23. As explained below, a motor (notshown) drives the take-up roller 23 to advance the pad 40 across thesub-pad 50 along a travel path T-T. The motor can also drive the supplyroller 24. The first idler roller 21 a and the first guide roller 22 apress an operative portion of the pad 40 against the sub-pad 50 to holdthe pad 40 stationary during operation.

[0003] The planarizing machine 10 also has a carrier assembly 30 totranslate a substrate 12 over the polishing pad 40. In one embodiment,the carrier assembly 30 has a head 31 to pick up, hold and release thesubstrate 12 at appropriate stages of the planarizing process. Thecarrier assembly 30 also has a support gantry 34 and a drive assembly 35that can move along the gantry 34. The drive assembly 35 has an actuator36, a driveshaft 37 coupled to the actuator 36, and an arm 38 projectingfrom the driveshaft 37. The arm 38 carries the head 31 via a terminalshaft 39. The actuator 36 orbits the head 31 about an axis B-B (asindicated by arrow R₁) and can rotate the head 31 (as indicated by arrowR₂) to move the substrate 12 over the polishing pad 40 while aplanarizing fluid 43 flows from a plurality of nozzles 45 in the head31. The planarizing fluid 43 may be a conventional CMP slurry withabrasive particles and chemicals that etch and/or oxidize the substrate12, or the planarizing fluid 43 may be a non-abrasive planarizingsolution without abrasive particles. In most CMP applications,conventional CMP slurries are used on conventional polishing pads, andplanarizing solutions without abrasive particles are used onfixed-abrasive polishing pads.

[0004] In the operation of the planarizing machine 10, the polishing pad40 moves across the sub-pad 50 along the travel path T-T either duringor between planarizing cycles to change the particular portion of thepolishing pad 40 in the planarizing zone A. For example, the supply andtake-up rollers 24, 23 can drive the polishing pad 40 betweenplanarizing cycles such that a point P moves incrementally across thesub-pad 50 to a number of intermediate locations I₁, I₂, etc.Alternatively, the rollers 24, 23 may drive the polishing pad 40 betweenplanarizing cycles such that the point P moves all the way across thesub-pad 50 to completely remove a used portion of the polishing pad 40from the planarizing zone A. The rollers 24, 23 may also continuouslydrive the polishing pad 40 at a slow rate during a planarizing cyclesuch that the point P moves continuously across the sub-pad 50 duringplanarization. In any case, the motion of the polishing pad 40 isgenerally relatively slow when the substrate 12 engages the polishingpad 40 and the relative motion between the substrate 12 and thepolishing pad 40 is primarily due to the motion of the head 31.

[0005] One drawback with the apparatus shown in FIG. 1 is that debriscan become caught between the polishing pad 40 and the sub-pad 50. Thedebris can cause a local bump or other non-uniformity in the polishingpad 40 which can create a corresponding non-uniformity in the substrate12 and/or can cause the polishing pad 40 to wear in a non-uniformmanner.

[0006] A further drawback is that the polishing pad 40 can adhere to thesub-pad 50 during planarization. This adhesive bond must be broken inorder to advance the polishing pad 40. In one conventional method, theidler rollers 21 a, 21 b and/or the guide roller 22 a are actuated tomove the polishing pad 40 normal to the upper surface of the sub-pad 50and break the adhesive bond. However, moving the polishing pad 40 normalto the sub-pad 50 can flex the polishing pad 40 and cause cracks, pits,and other defects to form in the polishing pad 40, which can in turncreate non-uniformities in the planarized surface of the substrate 12.

[0007] Another drawback is that the polishing pad 40 and the sub-pad 50can wear or abrade as they rub against each other. Accordingly, thepolishing pad 40 and the sub-pad 50 may need to be replaced on afrequent basis and/or the polishing pad 40 may develop non-uniformities.

[0008] One conventional CMP apparatus which may address some of theforegoing drawbacks includes a polishing pad that forms a continuousloop and that moves a high speed relative to the substrate, in themanner of a belt sander. FIG. 2 is a partially schematic side elevationview of one such conventional CMP apparatus 10 a having a continuouspolishing pad 40 a extending around two rollers 25. The polishing pad 40a can be supported by a continuous support band 41, formed from aflexible material, such as a thin sheet of stainless steel. A pair ofplatens 20 a provide additional support for the polishing pad 40 a attwo opposing planarizing stations. Two carriers 30 a, each aligned withone of the platens 20 a can each bias a substrate 12 against opposingoutwardly-facing portions of a planarizing surface 42 a of the polishingpad 40 a. Devices such as the apparatus 10 a shown in FIG. 2 and havingvertically oriented planarizing stations are available from Aplex, Inc.of Sunnyvale, Calif. under the name AVERA™. Generally similar deviceshaving a horizontally-oriented polishing pad 40 a and a single carrier30 a are available from Lam Research Corporation of Fremont, Calif.

[0009] During operation, the continuous polishing pad 40 a moves at arelatively high speed around the rollers 25 while the carriers 30 apress the substrates 12 against the polishing pad 40 a. An abrasiveslurry is introduced to the planarizing surface 42 a of the polishingpad 40 a so that the slurry, in combination with the motion of thepolishing pad 40 a relative to the substrates 12, mechanically removesmaterial from the substrates 12.

[0010] One drawback with the apparatus 10 a shown in FIG. 2 is that thepolishing pad 40 a must move at a high speed to effectively planarizethe substrates 12. The high-speed polishing pad 40 a can present asafety hazard to personnel positioned nearby, for example, if thepolishing pad 40 a should break, loosen, or otherwise malfunction duringoperation.

[0011] Another drawback is that the combination of the polishing pad 40a and the support band 41 may also wear more quickly than otherpolishing pads because both the planarizing surface 42 a of thepolishing pad 40 a and a rear surface 44 of the support band 41 rubagainst relatively hard surfaces (i.e., the polishing pad 40 a rubsagainst the substrate 12 and the support band 41 rubs against the platen20 a). This drawback can be serious because, once a defect forms in thepolishing pad 40 a, it can affect each subsequent substrate 12.

[0012] Still another drawback is that the interface between the supportband 41 and the platens 20 a can be difficult to seal, due to the highspeed of the support band 41. Accordingly, the abrasive slurry can seepbetween and abrade the support band 41 and the platens 20 a.

SUMMARY OF THE INVENTION

[0013] The present invention is directed to methods and apparatuses forplanarizing microelectronic substrates. In one aspect of the invention,the apparatus can include a platen that supports a movable support padwhich in turn supports a polishing pad against which the substrate ispressed to remove material from the substrate. The polishing pad can bean elongated web-format type pad that moves across the platen between orduring planarizing cycles. The support pad can move at approximately thesame rate as the polishing pad, reducing or eliminating relative motionbetween the two when they are in contact with each other and alignedwith the platen.

[0014] In one aspect of the invention, the apparatus can includecleaning and/or milling devices to treat the surfaces of the polishingpad and/or the support pad before they engage each other. The supportpad can be a continuous loop or can extend from a supply roller to atake-up roller. The platen can also be in the form of a continuous loopor an elongated member that extends from a supply roller to a take-uproller and can be integrated with the support pad in a further aspect ofthe invention. The platen can be supported by rollers, fluid jets, or apressurized bladder, and in yet a further aspect of the invention, caninclude orifices for directing fluid against the support pad to furtherreduce the likelihood for abrasive contact between the support pad andthe platen.

[0015] In a method in accordance with an aspect of the invention, atleast part of the support pad can be positioned between the platen andthe polishing pad of a planarizing machine. The polishing pad can bemoved at a first rate to move a first portion of the polishing pad intoalignment with the platen while moving a second portion of the polishingpad out of alignment with the platen. The support pad can be moved at asecond rate approximately the same as the first rate to engage a firstportion of the support pad with the first portion of the polishing padand disengage a second portion of the support pad from the secondportion of the polishing pad. In one aspect of the invention, the platencan be movable along with the support pad and can be tensioned bydirecting a flow of fluid toward the platen, biasing a roller againstthe platen or pressing a bladder against the platen.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016]FIG. 1 is a partially schematic, front isometric view of aweb-format planarizing machine in accordance with the prior art.

[0017]FIG. 2 is a partially schematic, side elevation view of aplanarizing machine having a continuous polishing pad in accordance withthe prior art.

[0018]FIG. 3 is a partially schematic, side elevation view of aplanarizing machine having a movable support pad in accordance with anembodiment of the invention.

[0019]FIG. 4 is a partially schematic, side elevation view of a portionof the apparatus shown in FIG. 3.

[0020]FIG. 5 is a partially schematic, side elevation view of aplanarizing machine having a movable, non-continuous support pad inaccordance with another embodiment of the invention.

[0021]FIG. 6 is a partially schematic, side elevation view of aplanarizing machine having a support pad coupled to a movable platen inaccordance with yet another embodiment of the invention.

[0022]FIG. 7 is a partially schematic, side elevation view of aplanarizing machine having a segmented platen in accordance with stillanother embodiment of the invention.

[0023]FIG. 8 is a partially schematic, partial cross-sectional sideelevation view of a planarizing machine having a movable, non-continuousplaten supported by a rotating bladder in accordance with anotherembodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0024] The present invention is directed towards methods and apparatusesfor planarizing microelectronic substrates and/or substrate assemblies.Many specific details of certain embodiments of the invention are setforth in the following description and in FIGS. 3-8 to provide athorough understanding of such embodiments. One skilled in the art,however, will understand that the present invention may have additionalembodiments, or that the invention may be practiced without several ofthe details described in the following description.

[0025]FIG. 3 is a partially schematic, side elevation view of aplanarizing machine 110 having a polishing pad 140 supported on a movingsupport pad 150. The polishing pad 140 can extend from a supply roller124 across a platen 120 to a take-up roller 123, while being controlledand guided by two idler rollers 121 a, 121 b and two guide rollers 122a, 122 b, generally as was discussed above. The polishing pad 140 canhave a planarizing surface 142 facing toward a substrate or substrateassembly 112 and a back surface 141 facing opposite the planarizingsurface 142. A carrier assembly 130 positioned adjacent the polishingpad 140 can include a head 131 that biases the substrate 112 against thepolishing pad 140 during operation. An actuator 135 can move the head131 relative to the polishing pad 140 to remove material from thesubstrate 112. The polishing pad 140 can advance from the supply roller124 to the take-up roller 123 either between or during planarizationcycles, in a manner generally similar to that discussed above.

[0026] The support pad 150 fits between the back surface 141 of thepolishing pad 140 and a support surface 125 of the platen 120, and canmove with the polishing pad 140 across the platen 120. For example, inone embodiment, the support pad 150 forms a continuous loop that extendsaround two support pad rollers 151 (shown as a left roller 151 a and aright roller 151 b) positioned on opposite sides of the platen 120. Anupper leg of the loop moves from left to right along with the polishingpad 140 (as indicated by arrow 145) and a lower leg of the loop movesfrom right to left (as indicated by arrow 146). In one aspect of thisembodiment, the support pad rollers 151 are rotatable but unpowered, andthe frictional force between the polishing pad 140 and the support pad150 is sufficient to slide the support pad 140 over the platen 120 asthe polishing pad 140 advances from the supply roller 124 to the take-uproller 123. Alternatively, either or both of the support pad rollers 151can be powered. In any case, the support pad 150 can move relative tothe platen 120 at approximately the same rate as does the polishing pad140 so that the portion of the support pad 150 between the polishing pad140 and the platen 120 is generally fixed relative to the polishing pad140.

[0027] The apparatus 110 can include cleaning devices 170 and a millingdevice 180 that treat the polishing pad 140 and the support pad 150before they come together on the platen 120. Further details of thestructure and operation of the cleaning devices 170, the milling device180 and the support pad 150 will be discussed below with reference toFIG. 4.

[0028]FIG. 4 is a detailed side elevation view of a portion of theapparatus 110 shown in FIG. 3. As shown in FIG. 4, the support pad 150can include a pad body 160 having a composite structure with an innerlayer 152 facing toward the platen 120, an outer layer 153 facingopposite the inner layer 152, and a core 154 between the inner and outerlayers 152, 153. In one embodiment, the inner and outer layers 152, 153can include a relatively rigid, incompressible material, such asfiberglass or Mylar®, and the core 154 can include a relatively flexibleor compressible material, such as a gel or a foam, including, forexample, a urethane foam. Alternatively, the pad body 160 can have auniform composition that can include either a relatively compressiblematerial or a relatively incompressible material. In any case, thesupport pad 150 can reduce the effect of contaminants on the uniformityof the planarizing surface 142. For example, when the support pad 150 isat least partially compressible, it can flex to reduce the effect on theplanarizing surface 142 of a contaminant trapped between the support pad150 and the platen 120. When the support pad 150 is more rigid, it candistribute the effect of the contaminant over a large area, which canalso reduce the effect of the contaminant on the uniformity of theplanarizing surface 142.

[0029] The support pad 150 can reduce the effect of contaminants thatmight be positioned between the support pad 150 and the platen 120, asdiscussed above. The cleaning devices 170 (shown as a fluid system 170 aand a brush 170 b) and the milling device 180 can reduce the likelihoodfor contaminants to become trapped between the support pad 150 and thepolishing pad 140 by treating the surfaces of the polishing pad 140and/or the support pad 150 before the two engage each other and passover the platen 120. For example, the fluid system 170 a can include amanifold 171 having a plurality of apertures 173 (shown as anupward-facing aperture 173 a facing toward the polishing pad 140 and adownward-facing aperture 173 b facing toward the support pad 150). Themanifold 171 can be coupled with a conduit 172 to a fluid source (notshown), such as a source of liquid or gas. The fluid can be pumpedthrough the manifold 171 and the orifices 173 to impinge on and washcontaminants from the polishing pad 140 and the support pad 150. Forexample, the manifold 171 can be coupled to both a liquid source and agas source to clean the polishing pad 140 and the support pad 150 withliquid and then dry the polishing pad 140 and the support pad 150 withthe gas. Alternatively, the conduit 172 can be coupled to a vacuumsource (not shown) for removing the contaminants under the force of avacuum.

[0030] The brush 170 b can include bristles 174 facing toward thepolishing pad 140 and/or the support pad 150 to scrub contaminantstherefrom. In one aspect of this embodiment, the brush 170 b can becoupled to an actuator (not shown) to move the brush 170 b intoengagement with the polishing pad 140 and/or the support pad 150 duringa cleaning cycle and out of engagement after the cleaning cycle iscomplete. In one embodiment, both the brush 170 b and the fluid system170 a can be positioned adjacent the outer layer 153. Alternatively, thebrush 170 b can include bristles 174 adjacent the inner layer 152 andthe fluid system 170 a can include orifices 173 directed toward theinner layer 152 for removing contaminants from the inner layer 152.

[0031] The milling device 180 can include a head 181 having sharpenedsurfaces 183 for removing a layer of material from the support pad 150.The head 181 can be coupled to an actuator 182 that moves the head 181into and out of engagement with the support pad 150 and that rotates orotherwise moves the head 181 in the plane of the support pad 150 forremoving material from the support pad 150. In one aspect of thisembodiment, the head 181 can be positioned adjacent to the outer layer153 of the support pad 150 to form a smooth surface at the outer layer(for example, if the outer layer 153 becomes abraded during use).Alternatively, the head 181 can be positioned proximate to the innerlayer 152 of the support pad 150 which may become abraded as a result ofcontact with the platen 120. In another embodiment, one head 181 can bepositioned adjacent the inner layer 152 and a second head 181 can bepositioned adjacent the outer layer 153 to smooth both opposite facingsurfaces of the support pad 150.

[0032] In operation, the polishing pad 140 moves over the platen 120from the supply roller 124 (FIG. 3) to the take-up roller 123 (FIG. 3),either between or during planarizing cycles. As the polishing pad 140advances over the platen 120, an incoming portion C of the polishing pad140 moves into alignment with the platen 120 so that it is positioneddirectly opposite the support surface 125 of the platen 120. At the sametime, an outgoing portion D of the polishing pad 140 moves out ofalignment with the platen 120. As the polishing pad 140 moves relativeto the platen 120, the support pad 150 moves at approximately the samerate so that an incoming portion E of the support pad 150 moves intoalignment with the platen 120 between the platen 120 and the polishingpad 140, and an outgoing portion F of the support pad 150 moves out ofalignment with the platen 120. The incoming portion E of the support pad150 supports the incoming portion C of the polishing pad 140 relative tothe platen 120 while the carrier assembly 130 (FIG. 3) presses thesubstrate 112 (FIG. 3) against the polishing pad 140.

[0033] One feature of the apparatus 110 shown in FIGS. 3 and 4 is thatthe support pad 150 moves together with the polishing pad 140 relativeto the platen 120. One advantage of this feature is that the polishingpad 140 will not wear as a result of relative motion with the supportpad 150 because the two move together at approximately the same ratewhen they are in contact with each other. Any wear due to relativemotion with the platen 120 is instead borne by the support pad 150,which bears against the fixed platen 120. Accordingly, the support pad150 can include materials selected for abrasion resistance, oralternatively, the support pad 150 can include relatively inexpensivematerials that may not be particularly wear-resistant, but areeconomical to replace.

[0034] Another advantage is that it is not necessary to move the guiderollers 122 (FIG. 3) and/or the idler rollers 121 (FIG. 3) normal to thepolishing pad 140 to force the polishing pad 140 out of engagement withthe support pad 150. Instead, the polishing pad 140 and the support pad150 separate from each other as the polishing pad 140 passes over thefirst guide roller 122 a and the support pad 150 diverges and passesover the right roller 151 b. The interfacing surfaces of the polishingpad 140 and the support pad 150 can diverge even if the interfacingsurfaces are wet, so that the interfacing surfaces can be cleansed witha liquid without substantially affecting the manner in which the supportpad 150 separates from the polishing pad 140.

[0035] Yet another feature of the apparatus 110 is that the cleaningdevice 170 can reduce the likelihood for contaminants to become lodgedbetween the polishing pad 140 and the support pad 150, and the millingdevice 180 can increase the planarity of the support pad 150.Accordingly, the polishing pad 140 and the support pad 150 can be lesslikely to develop bulges or other non-uniformities that reduce theplanarity of the planarizing surface 142 and therefore the substrate112. Furthermore, should contaminants become trapped between the supportpad 150 and the platen 120, the effect of such contaminants on theplanarizing surface 142 can be reduced (compared to the effect of acontaminant trapped between a polishing pad and a support pad, such asis shown in FIG. 1) because the support pad 150 can either flex toaccommodate the contaminant or distribute the effect of the contaminantover a large area.

[0036]FIG. 5 is a partially schematic, side elevation view of aplanarizing apparatus 210 having a non-continuous support pad 250 thatsupports a polishing pad 240 in accordance with another embodiment ofthe invention. The polishing pad 240 can advance from a supply roller224, past idler rollers 221 a, 221 b and to a take-up roller 223 in amanner generally similar to that discussed above with reference to FIGS.3 and 4. The support pad 250 is initially wound on a first roller 251 aand extends across a platen 220 to a second roller 251 b. Support padidler rollers 255 a and 255 b can tension the support pad 250 against asupport surface 225 of the platen 220. Accordingly, the support pad 250can unwind from the first roller 251 a across the platen 220 and ontothe second roller 251 b in a manner generally similar to that discussedabove with reference to the polishing pad 140 shown in FIGS. 3 and 4. Inone aspect of this embodiment, the second roller 251 b is powered towind the support pad 250. Alternatively, both the first and secondrollers 251 can be powered. In either case, the roller(s) 251 canadvance the support pad 250 across the platen 220 at approximately thesame rate as the polishing pad 240 advances across the platen 220.

[0037] In one embodiment, the support pad 250 can be disposed of once itis completely wound up on the second roller 251 b. Alternatively, thesupport pad 250 can be rewound onto the first roller 251 a and reused.In either case, the support pad 250 can have a length approximately thesame as the length of the polishing pad 240 (in one embodiment), so thatthe polishing pad 240 and the support pad 250 become completely wound upon their respective rollers at approximately the same time. Accordingly,the polishing pad 240 and the support pad 250 can be changed or rewoundat the same time.

[0038] In one embodiment, the platen 220 can include a manifold 226having perforations or orifices 229 extending through the supportsurface 225 adjacent to the support pad 250. The manifold 226 can becoupled with a conduit 227 to a source of pressurized liquid or gas 228.In operation, the source 228 can supply liquid or gas to the manifold226 and through the orifices 229 at a rate sufficient to separate atleast a portion of the support pad 250 from the support surface 225.Accordingly, the size and spacing of the orifices 227 and the pressureof the fluid from the source 228 can be selected to separate the supportpad 250 from the support surface 225 by a selected amount. An advantageof this feature is that it can reduce the friction between the supportpad 250 and the platen 220 as the support pad 250 advances across theplaten 220. In an alternate arrangement, suitable for an apparatushaving a fixed support pad such as the one shown in FIG. 1, the supportpad can have orifices aligned with the orifices of the manifold so thatthe pressurized liquid or gas can separate the polishing pad from thesupport pad.

[0039] Another feature of the apparatus 210 is that the non-continuoussupport pad 250 can include relatively inexpensive materials so that thesupport pad 250 can be economically replaced at the same time as thepolishing pad 240. Conversely, a feature of the continuous support pad150 (FIGS. 3 and 4) is that it can last through several polishing pads140 and/or several cycles of a single polishing pad 140.

[0040]FIG. 6 is a partially schematic, side elevation view of anapparatus 310 having a continuous support pad 350 integrated with acontinuous platen 320 in accordance with another embodiment of theinvention. The continuous support pad 350 can include materialsgenerally similar to those discussed above with reference to FIGS. 3 and4 and can move into and out of engagement with a polishing pad 340 in amanner generally similar to that discussed above with reference to FIGS.3 and 4. The platen 320 can include a continuous loop formed from agenerally incompressible, relatively flexible material, such as a thinstainless steel sheet and can carry the support pad 350 over and aroundsupport pad rollers 351 (shown as a left support pad roller 351 a and aright support pad roller 351 b).

[0041] In one embodiment, the support pad 350 and the platen 320 can betensioned over the support pad rollers 351 by a tensioning device, suchas an idler roller 355 that presses upwardly against the lower leg ofthe loop formed by the support pad 350 and the platen 320.Alternatively, other devices can provide a flat surface that supportsthe polishing pad 340. For example, in one embodiment, the apparatus 310can include a manifold 311 having a plurality of jet orifices 315directed upwardly toward a back side 326 of the upper leg of the loop.The manifold 311 can be coupled to a conduit 316, which is in turncoupled to a source of pressurized fluid, such as pressurized water orpressurized air which is forced through the orifices 315 to tension theplaten 320 and the support pad 350. Alternatively, the manifold 311 canbe positioned adjacent the lower leg of the loop (at approximately thelocation of the idler roller 355) with the jet orifices 315 directedupwardly against the lower leg in addition to or in lieu of the idlerroller 355. An advantage of tensioning the lower leg is that the upperleg is less likely to bow upwardly.

[0042] One feature of the apparatus 310 shown in FIG. 6 is that iteliminates relative motion between the support pad 350 and the platen320. Accordingly, an advantage of the apparatus 310 is that it canreduce the wear on the support pad 350, which can increase the life ofthe support pad 350 and reduce the frequency with which the support pad350 may need to be replaced. A further advantage is that by integratingthe support pad 350 with the platen 320, the apparatus 310 can eliminatethe possibility for contaminants to become caught between the supportpad 350 and the platen 320, further reducing the likelihood thatcontaminants can reduce the planarity of the polishing pad 340.

[0043]FIG. 7 is a partially schematic, side elevation view of anapparatus 410 having a segmented platen 420 connected to a support pad450, both of which support a polishing pad 440 in accordance withanother embodiment of the invention. The platen 420 can include aplurality of links 427 pivotally coupled to each other with pins 428 toform a continuous loop extending around two rollers 451 (shown as a leftroller 451 a and a right roller 451 b) generally in the manner of achain or tank trend. In one aspect of this embodiment, the rollers 451can each include teeth 456 to engage the links 427 and align the links427 as they pass over the rollers 451. Alternatively, the platen 420 caninclude other segmented arrangements and the roller can include othercorresponding features for guiding the platen 420.

[0044] In one embodiment, the apparatus 410 can also include a pluralityof support rollers 458 positioned between the rollers 451 along theupper leg of the loop formed by the platen 420 and support pad 450 tosupport the platen 420 and the support pad 450 in the region between therollers 451. An idler roller 455 can be positioned adjacent the lowerleg of the loop to bias the platen 420 and the support pad 450 upwardlyand tension these components relative to the rollers 451, either inaddition to or in lieu of the support rollers 458.

[0045] In one embodiment, the support pad 450 can include a plurality ofsegments 457, each separately attached to one of the links 427. Thesegments 457 can be closely spaced to provide a nearly continuoussupport surface for the polishing pad 440. Alternatively, the supportpad 450 can be continuous, for example, by making the connection betweenthe support pad 450 and the links 427 flexible and/or making the supportpad 450 itself flexible, so that the support pad 450 can bend around therollers 451. In yet another alternate embodiment, both the polishing pad440 and the support pad 450 can be elongated, non-continuous pads thatextend between corresponding supply rollers and take-up rollers,generally as discussed above with reference to FIG. 5. Accordingly, thesupport pad 450 can be removed and/or replaced without removing theplaten 420. In any case, the support pad 450 can engage with anddisengage from the polishing pad 440 (which unwinds from a supply roll424 and winds up onto a take-up roller 423) in a manner generallysimilar to that discussed above with reference to FIGS. 3 and 4.

[0046]FIG. 8 is a partially schematic, partial cross-sectional sideelevation view of a planarizing machine 510 having a movable,non-continuous platen 520 supported by a rotating bladder 590 inaccordance with another embodiment of the invention. The bladder 590 canbe formed from an at least partially fluid tight membrane folded uponitself to define an interior region 594 filled with a fluid, such aswater or air. The bladder 590 has a cross-sectional shape that forms aloop having an upper leg 591 adjacent the platen 520 and a lower leg 592opposite the upper leg 591. The upper leg 591 can support the platen 520and can move from left to right as indicated by arrow 545 along with theplaten 520 as the platen 520 unwinds from a supply roller 544 to atake-up roller 543. The lower leg 592 of the bladder 590 can move fromright to left as indicated by arrow 546 and can be supported by aplurality of bladder rollers 593 that rotatably engage the lower leg592. Accordingly, the bladder 590 can bias the platen 520 to a flatposition while minimizing abrasive contact between the platen 520 andthe bladder 590 because the two move at the same rate when they are incontact with each other.

[0047] In one embodiment, the apparatus 510 can further include anon-continuous support pad 550 that unwinds from a supply roller 551 aand winds up onto a take-up roller 551 b. The apparatus 510 can furtherinclude a non-continuous polishing pad 540 that extends from a supplyroller 524 to a take-up roller 523. The platen 520, the support pad 550and the polishing pad 540 can each pass over separate left idler rollers521 a and right idler rollers 521 b and can come together over a leftguide roller 522 a before passing over the bladder 590. After passingover the bladder 590, the platen 520, the support pad 550 and thepolishing pad 540 can pass over a right guide roller 522 b, from whichthe platen 520, the support pad 550 and the polishing pad 540 diverge.

[0048] In an alternate arrangement, the platen 520 can form a continuousloop that extends annularly around the bladder 590. In a further aspectof this embodiment, the support pad 550 can be integrated with theplaten 520, in a manner similar to that discussed above with referenceto FIGS. 6 or 7. In any case, one feature of the apparatus 510 is thatthe polishing pad 540, the support pad 550, the platen 520, and thebladder 590 each move at approximately the same linear rate when theyare in contact with each other. Accordingly, the likelihood for abrasionbetween these components (which can reduce the expected service life ofthe components), can be significantly reduced in comparison to someconventional devices.

[0049] The apparatus 510 can also include a cleaning device (such as thedevices 170 discussed above with reference to FIG. 4) and/or a millingdevice (such as the device 180 discussed above with reference to FIG. 4)positioned between the polishing pad 540 and the support pad 550, thesupport pad 550 and the platen 520, and/or the platen 520 and thebladder 590. Accordingly, another feature of the arrangement shown inFIG. 8 is that the likelihood for contaminants to become caught betweenthe polishing pad 540, the support pad 550 and/or the platen 520 can bereduced in comparison to some to conventional devices, reducing thelikelihood for creating non-uniformities at the planarizing surface 542and at the surface of the substrate 112.

[0050] From the foregoing it will be appreciated that, although specificembodiments of the invention have been described herein for purposes ofillustration, various modifications may be made without deviating fromthe spirit and scope of the invention. For example, certain featuresshown in the context of one embodiment of the invention may beincorporated in other embodiments as well. For instance, the cleaningdevices 170 and the milling device 180 shown in FIG. 4 may be used inconnection with any of the planarizing machines shown in FIGS. 5-8. Theperforated platen 220 shown in FIG. 5 can be used in conjunction withthe support pad 150 and polishing pad 140 shown in FIGS. 3 and 4. Any ofthe platen tensioning arrangements shown in FIGS. 6-8 can be used withany of the flexible or segmented platens shown in these Figures toprovide a flat support surface. Accordingly, the invention is notlimited except as by the appended claims.

1. An apparatus for planarizing a microelectronic substrate, comprising:a platen having a support surface; an elongated polishing pad moveablerelative to at least a portion of the platen between a first positionwith a portion of the polishing pad aligned with and facing toward atleast a portion of the support surface of the platen and a secondposition with the portion of the polishing pad out of alignment andfacing at least partially away from the support surface of the platen;and an elongated support pad movable with the polishing pad between afirst position with a portion of the support pad in contact with theportion of the polishing pad and a second position with the portion ofthe support pad out of contact with the portion of the polishing pad. 2.The apparatus of claim 1 wherein the support pad is elongated along anaxis and is compressible in a direction generally perpendicular to theaxis.
 3. The apparatus of claim 1 wherein the polishing pad extendsbetween a supply roll and a take-up roll.
 4. The apparatus of claim 1 ,further comprising a first roller positioned proximate to the platen anda second roller spaced apart from the first roller, wherein the supportpad forms a continuous loop extending around the first and secondrollers.
 5. The apparatus of claim 1 , further comprising a pad supplyroller and a pad take-up roller spaced apart from the pad supply roller,wherein the support pad is elongated between a first end coupled to thepad supply roller and a second end coupled to the pad take-up roll. 6.The apparatus of claim 1 wherein the platen includes an elongatedflexible member attached to the support pad and movable with the supportpad.
 7. The apparatus of claim 1 wherein the platen is movable relativeto the support pad between a first position with a portion of the platenin contact with the support pad and a second position with the portionof the platen separated from the support pad.
 8. The apparatus of claim7 , further comprising a platen supply roller and a platen take-uproller spaced apart from the platen supply roller, wherein the platen iselongated between a first end coupled to the platen supply roller and asecond end coupled to the platen take-up roller.
 9. The apparatus ofclaim 7 wherein the platen includes a plurality of links pivotablycoupled together to form a continuous loop, further wherein the supportpad includes a plurality of adjacent separable support pad portions,each support pad portion being attached to one of the links of theplaten.
 10. The apparatus of claim 9 , further comprising a plurality ofrollers rotatably engaged with the links of the platen for supportingthe platen and the support pad.
 11. The apparatus of claim 7 , furthercomprising: an at least partially fluid tight bladder having across-sectional shape that defines a loop with a first portion and asecond portion, the first portion of the loop being in contact with andsupporting the platen; and a plurality of rollers rotatably engaged withthe second portion of the loop.
 12. The apparatus of claim 1 , furthercomprising a cleaning device positioned proximate to an interfacebetween the portion of the polishing pad and the portion of the supportpad to remove material from at least one of the polishing pad and thesupport pad.
 13. The apparatus of claim 12 wherein the cleaning deviceis selected from a source of pressurized gas, a source of pressurizedliquid, a vacuum source and a brush.
 14. The apparatus of claim 12wherein the support pad has a first surface and a second surface facingopposite the first surface, further wherein the cleaning device ispositioned adjacent both surfaces of the support pad for cleaning theone surface.
 15. The apparatus of claim 1 , further comprising a millingdevice positioned proximate to the support pad and having at least onesharpened engaging surface positioned to remove a selected amount ofsupport pad material from the support pad.
 16. The apparatus of claim 14wherein the support pad has a first surface and a second surface facingopposite the first surface, further wherein the milling device ispositioned to remove material from both the first and second surfaces ofthe support pad.
 17. The apparatus of claim 1 wherein the polishing padis coupled to an actuator to move at a selected rate between the firstposition and the second position, further wherein the support pad isengaged with the polishing pad to move with the polishing pad at theselected rate.
 18. The apparatus of claim 1 wherein the support surfaceof the platen has a plurality of orifices coupleable to a source ofpressurized fluid for introducing the fluid between the support surfaceand the support pad to at least partially separate the support pad fromthe support surface.
 19. An apparatus for planarizing a microelectronicsubstrate, comprising: a platen having a support surface; an elongatedpolishing pad moveable relative to at least a portion of the platen tomove a first portion of the polishing pad into alignment with thesupport surface of the platen and move a second portion of the polishingpad spaced apart from the first portion out of alignment with thesupport surface of the platen; and a support pad positioned partiallybetween the polishing pad and the platen, the support pad being movablewith the polishing pad and having a first portion in contact with thefirst portion of the polishing pad when the first portion of thepolishing pad is aligned with the platen, the support pad further havinga second portion out of contact with the polishing pad when the secondportion of the polishing pad is out of alignment with the platen. 20.The apparatus of claim 19 wherein the polishing pad extends between asupply roller and a take-up roller.
 21. The apparatus of claim 19 ,further comprising a first roller positioned proximate to the platen anda second roller spaced apart from the first roller, wherein the supportpad forms a continuous loop extending around the first and secondrollers.
 22. The apparatus of claim 19 , further comprising a pad supplyroller and a pad take-up roller spaced apart from the pad supply roller,wherein the support pad is elongated between a first end coupled to thepad supply roller and a second end coupled to the pad take-up roller.23. The apparatus of claim 19 wherein the platen is movable relative tothe support pad between a first position with a portion of the platen incontact with the support pad and a second position with the portion ofthe platen separated from the support pad.
 24. The apparatus of claim 19wherein the platen includes an elongated flexible member attached to thesupport pad and movable with the support pad.
 25. The apparatus of claim19 wherein the platen includes a plurality of links coupled together toform a continuous loop, further wherein the support pad includes anelongated flexible member attached to the links of the platen.
 26. Theapparatus of claim 25 , further comprising a plurality of rollersrotatably engaged with the segmented links of the platen for supportingthe platen and the support pad.
 27. The apparatus of claim 19 , furthercomprising a cleaning device positioned adjacent an interface of thefirst portion of the polishing pad and the first portion of the supportpad to remove material from at least one of the polishing pad and thesupport pad.
 28. The apparatus of claim 27 wherein the cleaning deviceis selected from a source of pressurized gas, a source of pressurizedliquid, a vacuum source and a brush.
 29. The apparatus of claim 19 ,further comprising a milling device positioned proximate to the supportpad and having at least one sharpened engaging surface positioned toremove a selected amount of material from the support pad.
 30. Theapparatus of claim 19 wherein the polishing pad is coupled to anactuator to move at a selected rate relative to the portion of theplaten, further wherein the support pad is engaged with the polishingpad to move with the polishing pad at the selected rate.
 31. Theapparatus of claim 19 wherein the support surface of the platen has aplurality of orifices coupleable to a source of pressurized fluid forintroducing the fluid between the support surface and the support pad toat least partially separate the support pad from the support surface.32. A support pad for supporting a polishing pad of a web-formatplanarizing apparatus relative to a microelectronic substrate duringplanarization of the microelectronic substrates, the support padcomprising an elongated movable pad body having a first surface facingtoward the polishing pad when the support pad is installed on theplanarizing apparatus and a second surface facing opposite the firstsurface, the first surface including a first portion contacting thepolishing pad and a second portion spaced apart from the polishing padwhen the support pad is installed on the planarizing apparatus and thepolishing pad moves relative to the support pad.
 33. The support pad ofclaim 32 wherein the pad body defines a continuous loop and isconfigured to be engaged by at least two rollers for moving the pad bodyin a continuous path between the rollers.
 34. The support pad of claim32 wherein the pad body is elongated between a first end and a secondend spaced apart from the first end, the first end being coupleable to asupply roller and the second end being coupleable to a take-up roller.35. The support pad of claim 32 , further comprising a platen attachedto the pad body, the platen being generally incompressible in adirection generally perpendicular to at least one of the first andsecond surfaces of the pad body.
 36. The support pad of claim 35 whereinthe platen includes an elongated flexible sheet.
 37. The support pad ofclaim 35 wherein the pad body is elongated along an axis and the platenincludes a plurality of linked and generally rigid elements pivotablycoupled to each other to bend with the pad body as the pad body flexesin a direction generally perpendicular to the axis.
 38. The support padof claim 32 wherein the pad body includes at least one of fiberglass,polycarbonate, urethane and a gel.
 39. The support pad of claim 32wherein the pad body includes a generally compressible core positionedbetween two generally incompressible facing layers.
 40. An apparatus forsupporting a polishing pad during planarization of a microelectronicsubstrate, comprising: an elongated at least partially compressiblesupport pad having a first surface for engaging the polishing pad and asecond surface opposite the first surface; and a platen attached to thesecond surface of the support pad, the platen being generallyincompressible in a direction generally perpendicular to the secondsurface of the support pad, at least a portion of the platen and thesupport pad being movable with the polishing pad when the first surfaceof the support pad engages the polishing pad.
 41. The apparatus of claim40 wherein the support pad and the platen together form a continuousloop with the first surface of the support pad facing outward.
 42. Theapparatus of claim 40 wherein the support pad is elongated between afirst end and a second end, the platen is elongated between a first endand a second end, the first ends of the platen and the support pad areadjacent to each other and the second ends of the platen and the supportpads are adjacent to each other.
 43. The apparatus of claim 40 whereinthe platen includes a plurality of links pivotably coupled together toform a continuous flexible loop, further wherein the support pad isattached to the links of the platen.
 44. The apparatus of claim 40wherein the support pad includes at least one of fiberglass,polycarbonate, urethane and a gel.
 45. An apparatus for supporting apolishing pad during planarization of a microelectronic substrate,comprising: an elongated movable platen having a support surface forsupporting the polishing pad, the platen being movable relative to thepolishing pad between a first position and a second position when thepolishing pad is positioned proximate to the platen, a portion of thesupport surface being aligned with and facing toward at least a portionof the polishing pad when the platen is in the first position, theportion of the support surface being out of alignment and facing atleast partially away from the polishing pad when the platen is in thesecond position; and a tensioning device positioned proximate to themovable platen and operatively coupled to the platen to bias the portionof the support surface aligned with and facing toward at least a portionof the polishing pad toward a generally flat orientation.
 46. Theapparatus of claim 45 wherein the platen defines a continuous loopextending around a first roller and a second roller.
 47. The apparatusof claim 45 wherein the platen includes a plurality of links pivotablycoupled together to form the loop.
 48. The apparatus of claim 45 whereinthe platen is elongated between a first end coupled to a supply rollerand a second end coupled to a take-up roller.
 49. The apparatus of claim45 wherein the tensioning device includes a manifold coupled to a sourceof pressurized fluid, the manifold being in fluid communication with aplurality of orifices adjacent the platen.
 50. The apparatus of claim 45wherein the tensioning device includes at least one tensioning rollerpressing against the platen and movable relative to the platen to biasthe platen toward the generally flat orientation.
 51. The apparatus ofclaim 45 wherein the tensioning device includes: a bladder having afirst surface portion pressing against the platen and movable with theplaten in a first direction and a second surface portion opposite thefirst surface portion and movable in a second direction opposite thefirst direction; and a plurality of rollers adjacent the second surfaceportion of the bladder, the rollers rotatably engaging the secondsurface portion of the bladder and rotatable relative to the secondsurface of the bladder as the second surface portion of the bladdermoves in the second direction.
 52. The apparatus of claim 51 wherein thebladder contains a pressurized fluid.
 53. The apparatus of claim 45 ,further comprising a support pad positioned between the support surfaceof the platen and the polishing pad to space the support surface awayfrom the polishing pad while the support surface supports the polishingpad.
 54. The apparatus of claim 45 wherein the platen includes agenerally flexible, incompressible sheet.
 55. An apparatus forsupporting a polishing pad during planarization of a microelectronicsubstrate, comprising: a platen having a support surface with aplurality of orifices, the orifices being in fluid communication with asource of pressurized fluid for directing the fluid through the orificesand away from the platen; and an elongated support pad adjacent to thesupport surface of the platen, the support pad having a first surfacefacing away from the platen for engaging the polishing pad and a secondsurface facing toward the platen, at least a portion of the secondsurface of the support pad being separated from the support surface ofthe platen when the pressurized fluid passes through the orifices awayfrom the platen.
 56. The apparatus of claim 55 wherein the support padis moveable relative to the platen between a first position with aportion of the support pad in contact with a portion of the polishingpad and a second position with the portion of the support pad out ofcontact with the polishing pad.
 57. The apparatus of claim 55 , furthercomprising a pad supply roller and a pad take-up roller, wherein thesupport pad is elongated between a first end coupled to the pad supplyroller and a second end coupled to the pad take-up roller.
 58. Theapparatus of claim 55 , further comprising a first roller positionedproximate to the platen and a second roller spaced apart from the firstroller, wherein the support pad forms a continuous loop extending aroundthe first and second rollers.
 59. The apparatus of claim 55 wherein theorifices are in fluid communication with a source of pressurized liquid.60. The apparatus of claim 55 wherein the orifices are in fluidcommunication with a source of pressurized gas.
 61. A method forsupporting a polishing pad of a planarizing machine during planarizationof a microelectronic substrate, the method comprising: positioning atleast part of a support pad between a platen of the planarizing machineand the polishing pad; moving the polishing pad at a first rate to movea first portion of the polishing pad into alignment with the platenwhile moving a second portion of the polishing pad out of alignment withthe platen; and moving the support pad at a second rate approximatelythe same as the first rate to engage a first portion of the support padwith the first portion of the polishing pad and disengage a secondportion of the support pad from the polishing pad.
 62. The method ofclaim 61 wherein moving the polishing pad includes unrolling thepolishing pad from a supply roll and rolling the polishing pad up ontake-up roll.
 63. The method of claim 61 wherein the support pad forms acontinuous loop and moving the support pad includes rolling the supportpad continuously between a first roller and a second roller spaced apartfrom the first roller.
 64. The method of claim 61 wherein moving thesupport pad includes unrolling the support pad from a pad supply rolland rolling the support pad up on a take-up roll.
 65. The method ofclaim 61 wherein the support pad is attached to the platen and movingthe support pad includes moving the platen.
 66. The method of claim 61wherein the platen is movable relative to the support pad, furthercomprising moving the platen relative to the support pad between a firstposition with a portion of the platen contacting the support pad and asecond position with the portion of the platen separated from thesupport pad.
 67. The method of claim 66 wherein the platen includes aplurality of segmented links coupled together to form a continuous loop,further wherein moving the platen includes wrapping the plurality oflinks around at least two rollers and rolling the loop back and forthbetween the rollers.
 68. The method of claim 66 wherein moving theplaten includes unrolling the platen from a supply roller and rollingthe platen up on a take-up roller.
 69. The method of claim 61 , furthercomprising cleaning at least one of the polishing pad and the firstportion of the support pad before moving the first portion of thepolishing pad into alignment with the platen.
 70. The method of claim 61wherein cleaning at least one of the polishing pad and the first portionof the support pad includes exposing the at least one of the polishingpad and the support pad to a source of pressurized gas, a source ofpressurized liquid, a vacuum source and a brush.
 71. The method of claim61 , further comprising removing a selected amount of material from thesupport pad.
 72. The method of claim 61 wherein moving a first portionof the polishing pad into alignment with the platen includes positioningthe polishing pad proximate to the platen with a planarizing surface ofthe polishing pad generally parallel to the platen.
 73. The method ofclaim 61 wherein moving the polishing pad includes rolling the polishingpad on a take-up roll and moving the support pad includes frictionallyengaging the support pad with the polishing pad so that the support padmoves with the polishing pad.
 74. The method of claim 61 , furthercomprising separating at least a portion of the support pad from theplaten by directing a fluid toward the support pad through a pluralityof orifices in the platen.
 75. A method for supporting a polishing padduring planarization of a microelectronic substrate, comprising:engaging a support pad with the polishing pad; positioning at least aportion of the support pad between the polishing pad and a platen;moving the polishing pad and the portion of the support pad at the samerate relative to the platen.
 76. The method of claim 75 wherein movingthe polishing pad includes moving a first portion of the polishing padinto engagement with the support pad and moving a second portion of thepolishing pad spaced apart from the first portion of the polishing padout of engagement with the support pad.
 77. The method of claim 75wherein moving the polishing pad and the portion of the support pad atthe same rate includes frictionally engaging the polishing pad with theportion of the support pad so that the support pad moves with thepolishing pad.
 78. The method of claim 75 wherein moving the polishingpad includes unrolling the polishing pad from a supply roll and rollingthe polishing pad up on take-up roll.
 79. The method of claim 75 whereinthe support pad forms a continuous loop, further comprising moving thesupport pad by rolling the support pad continuously between a firstroller and a second roller spaced apart from the first roller.
 80. Themethod of claim 75 wherein moving the support pad includes unrolling thesupport pad from a pad supply roll and rolling the support pad up on atake-up roll.
 81. The method of claim 75 , further comprising cleaningat least one of the polishing pad and the first portion of the supportpad before positioning a portion of the support pad between thepolishing pad and the platen.
 82. The method of claim 75 whereincleaning at least one of the polishing pad and the first portion of thesupport pad exposing the at least one of the polishing pad and thesupport pad to a source of pressurized gas, a source of pressurizedliquid, a vacuum source and a brush.
 83. The method of claim 75 ,further comprising removing a selected amount of support pad materialfrom the support pad.
 84. A method for supporting a polishing pad on aplaten of a planarizing machine, comprising: inserting a portion of asupport pad between a portion of the polishing pad and a first portionof the platen; moving the portion of the polishing pad, the firstportion of the platen and the portion of the support pad togetherrelative to a second portion of the platen; separating the portion ofthe polishing pad from the portion of the support pad.
 85. The method ofclaim 84 wherein moving the portion of the polishing pad includesunrolling the polishing pad from a supply roll and rolling the polishingpad up on take-up roll.
 86. The method of claim 84 wherein the supportpad forms a continuous loop at least partially wrapped around first andsecond spaced apart rollers and moving the portion of the support padincludes rolling the support pad continuously between the first andsecond rollers.
 87. The method of claim 84 wherein moving the supportpad includes unrolling the support pad from a support pad supply rolland rolling the support pad up on a support pad take-up roll.
 88. Themethod of claim 84 wherein the platen includes a plurality of linkscoupled together to form a continuous loop, further wherein moving theplaten includes wrapping the plurality of links around at least tworollers and rotating at least one of the rollers to move the loop backand forth between the rollers.
 89. The method of claim 84 , furthercomprising cleaning at least one of the polishing pad and the firstportion of the support pad before moving the first portion of thepolishing pad into alignment with the platen.
 90. The method of claim 84wherein cleaning at least one of the polishing pad and the first portionof the support pad exposing the at least one of the polishing pad andthe support pad to a source of pressurized gas, a source of pressurizedliquid, a vacuum source and a brush.
 91. The method of claim 84 ,further comprising removing a selected amount of material from thesupport pad.
 92. The method of claim 84 wherein moving a first portionof the polishing pad into alignment with the platen includes positioningthe polishing pad proximate to the platen with a planarizing surface ofthe polishing pad generally parallel to the platen.
 93. A method forsupporting a polishing pad of a planarizing machine, comprising:providing a flexible platen having a support surface for supporting thepolishing pad; tensioning the platen to at least approximately flattenthe support surface; and moving the platen between a first position withthe support surface aligned with and facing toward the polishing pad anda second position with the support surface out of alignment and facingat least partially away from the polishing pad.
 94. The method of claim93 , further comprising inserting a support pad between the supportsurface of the platen and the polishing pad.
 95. The method of claim 93wherein tensioning the platen includes directing a flow of fluid towardthe platen.
 96. The method of claim 93 wherein tensioning the platenincludes biasing a roller against the platen.
 97. The method of claim 93wherein tensioning the platen includes pressing a first surface portionof a bladder against the platen, biasing a plurality of rollers againsta second surface portion of the bladder and rotating the bladder as theplaten moves between the first position and the second position suchthat the first surface portion of the bladder moves with the platen andthe second surface portion of the bladder rotates the rollers.
 98. Themethod of claim 93 wherein the platen forms a continuous loop having afirst portion proximate to the polishing pad and a second portion spacedapart from the first portion, further wherein tensioning the platenincludes directing a tensioning force to the first portion of theplaten.
 99. The method of claim 93 wherein the platen forms a continuousloop having a first portion proximate to the polishing pad and a secondportion spaced apart from the first portion, further wherein tensioningthe platen includes directing a tensioning force to the second portionof the platen.
 100. A method for supporting a polishing pad duringplanarization of a microelectronic substrate, comprising: positioning asupport pad proximate to a platen such that a first surface of thesupport pad faces the support surface of the platen and a second surfaceof the support pad faces away from the platen; positioning the polishingpad adjacent the second surface of the support pad; and supplyingpressurized fluid through orifices of the platen to separate a portionof the support pad from the support surface of the platen.
 101. Themethod of claim 100 wherein supplying a pressurized fluid includessupplying a pressurized liquid.
 102. The method of claim 100 whereinsupplying a pressurized fluid includes supplying a pressurized gas. 103.The method of claim 101 , further comprising advancing the support padand the polishing pad over the platen at approximately the same rate.104. The method of claim 103 wherein advancing the support pad includesunrolling the support pad from a supply roller and rolling the supportpad onto a take-up roller.
 105. The method of claim 103 whereinadvancing the support pad includes rolling the support pad in acontinuous loop between first and second spaced apart rollers.